1. Field of the Invention
The present invention relates to an image forming apparatus for printing an image on a sheet such as a print sheet, and, more particularly to an image forming apparatus that has a conveying path suitable for a thick paper while increasing a volume of sheets.
2. Description of the Related Art
There is known an image forming apparatus that has a recording head of an ink jet system and in which a head recording unit moves perpendicularly to a conveying direction of a sheet and performs image formation. In such an image forming apparatus, a sheet cassette is arranged below the head recording unit to increase a volume of sheets and sheets are fed from this sheet cassette. In this case, it is necessary to reduce a conveying path length by reason of, for example, securing printing speed. Therefore, a sheet fed from the sheet cassette passes through a conveying path having a small curvature radius. A U-turn conveying apparatus for reversing a sheet is disclosed in JP-A-2006-193317.
On the other hand, there is also known an image forming apparatus including means for feeding a sheet from a rear surface to secure a large curvature radius.
However, when the sheet cassette is arranged below the head recording unit, since the curvature radius of the conveying path is small, there is a problem in that, when hard paper having sturdiness of a certain degree or more such as a thick paper is fed, for example, creases are left in paper and paper jamming occurs. On the other hand, when the means for feeding a sheet from a rear surface is used, there is a problem in that, for example, dust accumulates when sheets are left untouched.
It is an object of the invention to provide an image forming apparatus and an image forming method that can prevent, when a sheet cassette is arranged below a head recording unit to increase a volume of sheets, creases from being left and paper jamming from occurring even if a thick paper is used.